hello every body
I have a question about the reflectivity of the following circuit.

If the length of the transmission line is 0, the reflection coefficient at the load is how much?
formula:
Reflection coeficient = (Zl-Zs)/(Zl+Zs)
is true?
thank you every one

 

please help me

 

Do the math. What does it tell you?

 

Wikipedia, where you got the diagram, says so, so it must be true.

 

Just because the transmission line has length zero does not change the amount of signal absorbed by the load. It follows that what is not absorbed by the must be reflected back to the source.

 

Wikipedia, where you got the diagram, says so, so it must be true.

Not always true, Wikipedia is not a reliable source.

 

I have never seen anything that has a 0 length or a 0 time.

 

I have never seen anything that has a 0 length or a 0 time.

Are you sure? Your wife told me about your honeymoon.

 

Hello,

Ha ha.

Is this really a valid question? A zero length transmission line isnt a transmission line anymore. A transmission line has characteristics based on its makeup and if there is no length then there is no parameters for the transmission line itself. A direct short has 0 impedance. Since the length is zero, how do we distinguish the transmitted signal from the reflected signal.
One of the parameters of a transmission line equation is the length, and if the length is zero then there must be no delay from one end to the other, in either direction.
Just some quick thoughts.

Where did this question originate?

 

in above pictủe,i thing length of transmition line be zero. how to caculate the coeficient at source

 

Hello,

Ha ha.

Is this really a valid question? A zero length transmission line isnt a transmission line anymore. A transmission line has characteristics based on its makeup and if there is no length then there is no parameters for the transmission line itself. A direct short has 0 impedance. Since the length is zero, how do we distinguish the transmitted signal from the reflected signal.
One of the parameters of a transmission line equation is the length, and if the length is zero then there must be no delay from one end to the other, in either direction.
Just some quick thoughts.

Where did this question originate?

but i seen in RF designs. the designs isbuild based on S parametter. for example

design based Sparameter with no transmition line,Why?
if the line is available, what is it being in the schematic
please help me

 

but i seen in RF designs. the designs isbuild based on S parametter. for example
View attachment 116607
design based Sparameter with no transmition line,Why?
if the line is available, what is it being in the schematic
please help me

The existence of a transmission line depends on the frequency of operation. In the millimeter wave region of the RF spectrum -- everything, including component leads and PCB traces, is a transmission line. At lower frequencies -- not so much. Impedance matching in circuits is maybe not as important as you might think for a variety of reasons.

 

The existence of a transmission line depends on the frequency of operation. In the millimeter wave region of the RF spectrum -- everything, including component leads and PCB traces, is a transmission line. At lower frequencies -- not so much. Impedance matching in circuits is maybe not as important as you might think for a variety of reasons.

OK Thank you so much.
I have a question about the formula for calculating the power of the incident wave



We can normalize the amplitude of waves to Z 0 :

I dont understand why

and

can you explain for me, please.
sorry for my english

 

These are just a set of definitions for talking about s-parameters. The unlabeled box between the two transmission lines contains an arbitrary collection of components connected in some fashion. We are not particularly concerned about the internal workings of the box; we intend to characterize the contents of the box by coming up with four parameters, as functions of frequency, that describe what happens with incident and reflected signals under certain conditions.

In order for these definitions to make sense a value of Zo must be defined. The transmission lines in the picture not required; they could be replaced by the appropriate generator and load.

Does that help?